1. Field of the Invention
The present invention relates to information transmission method and device for obtaining a search result (information) of more than one data type to respond to a request from a client.
2. Description of the Related Art
In recent years, various types of on-line information provider systems are available. An information provider system including an information providing center for providing information to an on-vehicle navigation system and the vehicle is one such example. Receiving a request from a vehicle for transmission of certain information, the information providing center searches its own database for the requested information and transmits a response to the request. Recent navigation systems can handle information such as news and advertising in addition to information on maps and route guidance. While responding to some transmission requests, such as a request for a road map around a destination, requires only one item of information, more than one item of information may be simultaneously needed to respond to other requests, such as a request for information on restaurants near a certain station A. The information providing center is usually formed by a server system equipped with a variety of databases for providing information so as to respond to clients"" requests for transmission of a variety of information. However, as the center may not store all the required information, it may have access to an external database system so as to retrieve information to be supplied as a response.
Search requests made from a vehicle to the information providing center include those for detailed maps covering a destination, news, information on facilities (location, services provided, and so on) the client wishes to use, and the like. When receiving a request to search for xe2x80x9crestaurants in a certain areaxe2x80x9d, for example, the information providing center searches the database for information on the restaurants of interest, and responds by sequentially transmitting the search results. The information on restaurants generally includes the address, telephone number, introduction articles, location, and photos of the restaurants showing their appearance. Such information is in the form of text, image, or audio data, or combination thereof, supplied from the information providing center.
At the vehicle, data transmitted from the information providing center can be sequentially presented at its display, or the information can be monitored with speech output. FIG. 8 schematically shows an example of a display showing information on restaurants.
Conventionally, however, the information providing center simply transmits search results in order, regardless of the amount of each piece of information in a response. If the information providing center first transmits a large amount of data to a vehicle, the data cannot be immediately presented on an on-vehicle display. In other words, clients (such as users of a mobile terminal on a vehicle or the like) feel that they are being kept waiting because a long time period is required for display of the data. If image data or the like is first transmitted, the users ay strongly feel that they are being kept waiting, whereby the users wonder if there is something wrong with a communication channel.
The present invention has been conceived to solve the above problem, and an object thereof is to provide an information transmission method and device for preventing, as much as possible, a client from getting an impression that they are being kept waiting, even if a large amount of data is contained in a response.
In order to achieve the above object, an information transmission method for a server to transmit a response to a client""s request for information transmission according to a first aspect of the present invention includes the steps of: identifying the type of data in the response; obtaining the amount of transmitted data for each data type in the response; controlling the order of data transmission based on the thus obtained amount of transmitted data for each data type; and transmitting the response in the data transmission order set by the above step of controlling the data transmission order.
An information transmission method for an information providing center to transmit a response to a request from a vehicle for information transmission according to a second aspect of the present invention includes the steps of: identifying the type of data in the response; obtaining the amount of transmitted data for each data type in the response; controlling the order of data transmission based on the thus obtained amount of transmitted data for each data type; and transmitting the response in the data transmission order set by the above step of controlling the data transmission order.
According to a third aspect of the present invention, the step of controlling the transmission order in the information transmission method of the above first or second aspect includes the step of sequentially arranging data in an ascending order so that the data of the type having the smallest data amount is put first in order.
According to a fourth aspect of the present invention, the step of controlling the transmission order in the information transmission method of the above first or second aspect includes the step of sequentially arranging data of a type in an ascending order so that the data having the smallest amount is put first in order among the data of that data type when a plurality of data items are contained in the data type.
According to a fifth aspect of the present invention, the information transmission method of the above first or second aspect further includes a step of dividing search results into units when a plurality of search results are included in a response, and the step of controlling the transmission order includes the step of determining data transmission order for each unit.
According to the above aspects, regardless of the order of search requests or search results (information) obtained by searching databases, data is arranged in an ascending order of the data amount for each data type and, when a plurality of data items are included in a data type, data is further arranged in an ascending order of the data amount for each type or unit so that data with the smallest amount is first transmitted. Since information is transmitted in the above manner, a client receiving the information does not feel that they are being kept waiting because the information begins appearing shortly after a search request is made.
According to a sixth aspect of the present invention, the above step of controlling the transmission order in the first or second aspect includes the step of dividing search operations into groups based on databases when a plurality of databases should be searched to obtain a response so as to control the data transmission order for each group. By thus performing a search on the basis of databases, overhead accompanied with switching databases is reduced, contributing to a reduction in time for retrieval of requested information. As a result, a client receiving the information does not feel kept waiting because he/she can receive the information more shortly after making a search request.
Especially, the method according to the second aspect which prevents a client from feeling kept waiting is very advantageous for a person on board because the person, who waits for the information in a vehicle that is relatively small in terms of space while moving to a destination or the like, would feel there is a longer wait relative to a general server system.
Further, an information transmission device according to the present invention includes means for implementing the information transmission method according to the above aspects.